In communication networks, in order to increase the reachable throughput of communication, MIMO (Multiple Input, Multiple Output) has been proposed widely. MIMO involves the use of multiple antennas at both the transmitter and receiver to improve communication performance. It indeed offers significant increases in data throughput without additional bandwidth or transmit power by higher spectral efficiency (more bits per second per hertz of bandwidth) and link reliability.
In an exemplary embodiment of the invention, a mobile communication network comprises a primary station (base station, or NodeB or eNodeB) which can communicate with at least one secondary station (mobile stations, or User Equipment, or UE) with MIMO streams, by using a plurality of primary station antennas and a plurality of secondary station antennas. In order to form the stream, the secondary station provides the primary station with information related to the state of the channel by transmitting CSI (channel state information) feedback to the primary station. Such CSI indicates an optimal or at least a preferred precoding vector to be used in order to maximise the reachable data rate of the corresponding spatially separable data streams transmitted by the primary station. This precoding vector can be a set of complex values to be applied to each antenna port of the primary station during transmission to direct the data stream towards the secondary station antennas.
However, the primary station may also select other precoding vectors to direct data streams towards different secondary stations. If the first secondary station does not select appropriate receive combining weights to apply to the signals received at its receive antennas, it may suffer adverse interference from the data streams directed at other secondary stations.